1. Technical Field
The present disclosure relates to an engine system in a vehicle that overrides an engine shut-down system based upon the operation of the air conditioner compressor of the vehicle.
2. Background
Full hybrid vehicles are vehicles that are equipped with a battery-powered motor that is capable of propelling the vehicle without assistance from an internal combustion engine. Mild hybrid and other “Stop/Start” vehicle system configurations are vehicles that enable engine to be turned off whenever the vehicle is coasting, braking, and/or stopped, yet restarted quickly when required. When the driver presses the gas pedal to accelerate the vehicle, the engine is required to restart quickly to accelerate the vehicle. As opposed to a full hybrid, mild hybrids do not have an exclusive electric-only mode of propulsion and therefore rely on the quick restart of the combustion engine to accelerate the vehicle on demand.
Conventional air conditioners are driven by the engine in a mild hybrid vehicle. During the time that the engine is in a shut-down mode, the compressor of the air conditioner is no longer powered by the engine, and therefore does not work to compress fluid in the air conditioning system. Therefore, air conditioning systems in mild hybrid vehicles lose effectiveness while the engine is temporarily shut down.
It is necessary to maintain passenger comfort while the engine of a mild hybrid is in shut-down mode. One way to maintain passenger comfort includes the use of a system that restarts the engine whenever the air in the vehicle cabin becomes too warm. One problem with this approach is that the engine may frequently stop and restart to reach and maintain an optimal cabin temperature. Frequent engine stopping and restarting may be referred to as “on/off busyness” that is objectionable to vehicle occupants. Another way to maintain passenger comfort includes the use of temperature sensors, humidity sensors, and sun load sensors to predict when the shut-down mode would be undesirable. These sensors are typically expensive and therefore undesirable in some vehicles. Algorithms are typically used in combination with these sensors to maintain passenger comfort.
There is currently a need for a cost effective system by eliminating or minimizing the use of sensors while assuring the comfort of vehicle occupants without unwanted turning off and restarting of the engine.